Cytokinin-Specific Modulation of Protocorm-Like Bodies (PLB) Formation and Shoot Organogenesis in Habenaria radiata L.

Rifa Munifah Hasibuan, Kazuhiko Takahashi, Deng Tingrong, Sakura Takahashi and Sakae Suzuki

Background and Objective: Habenaria radiata L. (white egret orchid) is a Near-Threatened terrestrial orchid which conservation cultivation depends on efficient in vitro propagation. Protocorm-like body (PLB) proliferation offers rapid clonal multiplication, whereas direct shoot organogenesis yields transplant-ready plantlets; both pathways are strongly regulated by cytokinin. We compared the effects of three cytokinin: 6-benzylaminopurine (BA); kinetin; thidiazuron (TDZ) on PLB and shoot induction in seed derived protocorms of H. radiata. Materials and Methods: The study evaluated cytokinin-mediated protocorm-like body (PLB) formation and shoot organogenesis in H. radiata ‘Aoba wild type’ under in vitro conditions. Seeds were germinated on half-strength MS medium and seedlings were treated with different cytokinins (BA, kinetin, TDZ). The PLB and shoot responses were assessed after 32 weeks and data were analyzed using one-way ANOVA at p<0.05 to identify the most effective hormonal treatment for large-scale propagation and conservation. Results: The TDZ (90% PLB) were the strongest inducers of PLB. By contrast, BA favored direct shoot formation. The results show that the nature of cytokinin influences the regeneration outcome in H. radiata showed that BA promote the growth of organogenesis shoots, while TDZ and kinetin explants promote toward somatic embryogenic PLB path. Conclusions: Selecting an appropriate cytokinin therefore allows propagation protocols to be tailored either to mass-produce PLB for scale-up or to generate shoot-bearing plantlets for rapid acclimatization. These insights advance the micropropagation for H. radiata and contribute to ex-situ conservation strategies for this orchid.

View Fulltext Back